1. Field of the Invention
This invention relates to a telecommunications analyzer to monitor, record and display transmission line performance and may also include means to monitor modem and interface performance.
2. Description of the Prior Art
Most existing data communication systems requiring an immediate transfer of data between a computer and a distant computer or I/O device normally use voice-grade telephone lines or special dedicated lines between locations as the transmission medium. To transfer data signals over this transmission medium, the DC output signals of the computer or terminal equipment is converted to an audio signal for transmission. At the remote site, the audio signal is reconverted to the original DC pulse signal.
When a data communications user installs his own system, he generally integrates a number of separate components or subsystems such as terminals, modems, printer, interfaces and the like into a complete data communications system. Often these components of subsystems are obtained from different vendors. As a result, once such an integrated system is assembled and operating, the problem of "trouble shooting" system malfunctions are generally compounded due to the various interfaces. All too often, a user's system remains inoperative, while representatives from the various vendors report that they have checked their portion of the system and found that it is operating properly.
Inherently, the transmission medium is subject to numerous environmental conditions which seriously affect various electrical parameters causing these parameters to exceed performance specifications. Specifically, the transmission medium is exposed to gain hits, phase jitter, impulse noise, C message notched noise, nonlinear distortion, frequency response distortion and envelope delay.
In addition, serious failures often arise from incompatibility in line control protocol between terminal and computer, terminal and modem, modem and modem, modem and phone-line interface, and software programs.
A number of test sets are available which test individual performance parameters such as bit-error-rate detecting systems, phase jitter/phase hit meters, impulse noise meters and C-message weighted noise meters. Obviously, when attempting to determine and isolate the source of improper or low system performance, a number of test sets are necessary. The attendant cost of purchasing and maintaining individual test sets may be prohibitive. Moreover, since the performance parameters are constantly changing to varying degrees, the inherent time factor associated in conducting these tests separately are often ineffective.
In addition, these test sets generally require a skilled technician to conduct and interpret the test results. Furthermore, there are usually no provisions for recording the test results which would allow for a more thorough analysis of the performance parameters with respect to time.
Thus, a need exists for an inexpensive portable system analyzer capable of monitoring, displaying and recording transmission line performance parameters with respect to time, simple enough for an unskilled technician to interpret and evaluate.